Abstract

The objective of this study was to develop a diagnostic model that allows for a highly specific diagnosis of chronic hypersensitivity pneumonitis using clinical and radiological variables alone. Chronic hypersensitivity pneumonitis and other interstitial lung disease cases were retrospectively identified from a longitudinal database. High-resolution CT scans were blindly scored for radiographic features (eg, ground-glass opacity, mosaic perfusion) as well as the radiologist's diagnostic impression. Candidate models were developed then evaluated using clinical and radiographic variables and assessed by the cross-validated C-statistic. Forty-four chronic hypersensitivity pneumonitis and eighty other interstitial lung disease cases were identified. Two models were selected based on their statistical performance, clinical applicability and face validity. Key model variables included age, down feather and/or bird exposure, radiographic presence of ground-glass opacity and mosaic perfusion and moderate or high confidence in the radiographic impression of chronic hypersensitivity pneumonitis. Models were internally validated with good performance, and cut-off values were established that resulted in high specificity for a diagnosis of chronic hypersensitivity pneumonitis.

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Comments

This is an usual paper from a group who has a large number of patients with chronic hypersensitivity pneumonitis diagnosed from lung biopsies, but who do not regularly perform differential cell counts on BAL or tests for sensitisation to common causes of HP. They have developed a diagnostic model which achieves a sensitivity of 50% with a specificity of 90%. The main contributing factors are the opinion of the radiologist on the CT, together with age and exposures to birds and/or down feathers. Other common causes of HP seem to omitted, so really this is a model of chronic HP due to avian antigens. Smoking, lung physiology clinical features do not appear in the model.

9/29/2016